This invention relates generally to control systems for appliances, and more particularly, to a control system for a refrigerator.
Known household appliances are available in various platforms having different structural features, operational features, and controls. For example, known refrigerator platforms include side-by-side single and double fresh food and freezer compartments, and vertically oriented fresh food and freezer compartments including top mounted freezer compartments, and bottom mounted freezer compartments. Conventionally, a different control system is used in each refrigerator platform. For example, a control system for a side-by-side refrigerator typically controls the freezer temperature by controlling operation of a mullion damper located between the fresh food compartment and the freezer compartment, a fresh food fan and a variable or multi-speed fan-speed evaporator fan. Top mount refrigerators and bottom mount refrigerators however, are available with and without a mullion damper, the absence or presence of which consequently affects the refrigerator controls. Other major appliances, including dishwashers, washing machines, dryers and ranges, are available in various platforms and employ different control schemes.
In case of power failure, at least some electronically controlled appliances typically include additional electronic components, such as a power failure detection circuit and a capacitive tank, that allow the system time to write data to system memory as the power is failing. By saving pertinent data, the appliance may recover more efficiently and without unnecessarily resetting itself when power is restored, especially when power outages are relatively brief. Thus, for example, a refrigerator cooling cycle or defrost cycle may be resumed from the point of power loss when power loss is brief and without significant effect on refrigerator conditions. Additional electronic components for writing data in a power loss, however, increase costs of the appliance.
In an exemplary embodiment, an appliance control system includes a controller having a processor and a memory including at least a first memory area and a second memory area so that a multiple write architecture may be used for storing data. The processor is configured to acquire appliance status data on a periodic basis, write the refrigerator status data to the first memory area and to the second memory area, and perform error detection upon the written data during refrigerator power-up. Upon power up, the controller determines the validity of data in one of the memory locations, or pages. If the data is determined to be invalid on one memory page, another memory page is used. Thus, by storing data redundantly in multiple memory pages with appropriate security measures, data may be retained for use on power-up without the expense of additional electronic components.
More specifically, for a refrigerator control system, the appliance status data includes at least one of a defrost time, last compression cycle time, and a water filter remainder time. The memory includes at least four memory areas, and about every thirty minutes, the processor writes status data to first and second memory locations, as well as calculates a Cyclic Redundancy Check value for the acquired data and stores the Cyclic Redundancy Check value in the third and fourth memory locations. Upon power-up, the processor re-calculates a Cyclic Redundancy Check value for the acquired refrigerator status data stored in the first memory location. The calculated Cyclic Redundancy Check value is compared to a stored Cyclic Redundancy Check value in the third memory location. If the calculated Cyclic Redundancy Check matches the stored Cyclic Redundancy Check, the data contained in the first memory location is restored and the controller resumes appliance operation.
If the calculated Cyclic Redundancy Check does not match the stored Cyclic Redundancy Check from the third memory location, the processor re-calculates a Cyclic Redundancy Check for the acquired refrigerator status data stored in the second memory location. The calculated Cyclic Redundancy Check is then compared to a stored Cyclic Redundancy Check value in the fourth memory location. If the calculated Cyclic Redundancy Check matches the stored Cyclic Redundancy Check, the data contained in the second memory location is restored and the controller resumes appliance operation.
If the calculated Cyclic Redundancy Check from data stored in the second memory location does not match the stored Cyclic Redundancy Check from the fourth memory location, the status data is reset to default values and the controller resumes appliance operation.
Thus, redundant data storage with error detection provides low cost data protection without additional electronic components with minimal risk of corrupted data in all of the memory locations.